Stucco mixer



Feb. 18, 1930.

s. c. CLARK STUCCO MIXER Filed June 8.v 1927 i5 Sheets-Sheet l Illllbl l' S. C. CLARK sTUcco MIXER Feb. 18, '1930.

Filed June 8., 1927 3 Sheets-Sheet 2 Feb. 18, 1930. s, C. CLARK 1,741,466

STUCGO `MIXER Filed June 8.v 1927 3 Shets-Sheet 5 Patented Feb. 18, 1930 UNITED STATES PATENT orifice SIDNEY C. CLARE, OF PORT CLINTON, OHIO, ASSIGNOR TO AMERICAN GYPSUM COM- IPANY, F PORT CLINTON, OHIO, A `CORINQRA'IION' OE OI-IIO` j, i

STUCCO MIXER Application led June 8, 1927. Sera1 No. 197,256.

This invention relates to'improvements in stucco mixers, and more particularly to an apparatus for mixing stucco or calcined gypsum in a dry powdered state with water or other ingredients required to form the wet plastic mix from which various gypsum products are made.

The object of the invention is to provide an improved method for the continuous mixing of stucco and water and operating on a different principle than has been followed heretofore, and one calculated to give better and more uniform results.

A further object of the invention is to proa vide a mixing apparatus designed to replace the ordinary so-called soaking belt heretofore generally used and forming a part of machines employed in the manufacture of gypsum products.

As well known in the gypsum industry, stucco is the term applied toV calcined gypsum, that is, the product obtained by calciningy or partly calcining the gypsumiock,'-a process consisting of heating the crushed rock in rotary kilns to drive 0E a certain percentage (roughly 8O of the water of crystallization. In its calcined state, the gypsum or stucco is a powdered substance and when subjected or mixed with water immediately absorbs an amount equivalent to that removed by calcination, and crystallization or setting immediately commences. In other words, the tendency of the stucco in the presence of water is to take up its normal water of crystallization content and to resume the crystalline formation possessed in its natural state as gypsum rock, Valthough of a finer and more uniform texture.

The proper treatment of, stucco in order to promote the formation of lthe crystalline structure upon which the strength and durability cf the finished product as a building or insulating material is dependent, requires first, that each particle of stucco be given ample opportunity of absorbing its full volume of water, and secondly, that as soon ask the absorption has been completed that the mass yof stucco be allowed to set as soon as possible without unnecessary agitation or disturbance. In other words, that the wet stucco be reduced to its final form without undue agitation or mixing. The reasons for this are two-fold: In the first place, ifl the particles of stucco do not absorb the required amount of' water, the crystallization process will be retarded and incomplete, andy secondly,- since the formation of crystals commences immediately in the presence of water, any

agitation or mixing thereafter necessarily `tends to break down the crystals and otherwise interfere with their normal formation, with theresult that the structure will be weak- .cned due to the interference with the crystal' the receiving end of the belt, andthence re- Y suming a straight line travel, passes beneath sets of mechanical mixers which stir the soaked stucco on the belt just before itis disl charged'for immediate use in the-making of the vparticular product.V

The formation of furrows is intended to increase the penetration of the dry stucco with the water, but as a practical matter, there are portions of the stucco near the bottom of the layer and particularly where the .depthr is greatest, which are not penetrated by the y water during the relatively short period of immersion, and asa consequence, there is not the requisite water absorption for .complete crystallization throughout thel entire mass. Moreover, since the setting of the stucco Com- 'mences'piinmediately upon immersion, itjfollows that the mixing to which lthe stucco is subjected. during theinitial stage of crystal formation, necessarily results inthe break- `ing'dovvn of the crystals and otherwise, interfering with the process of crystallization which should be permitted to take place With.- out undue disturbance. .Y In short,y this; s'ocalled soaking and .mixing process .in the c course of convertingY raw gypsum into a'` commercial product, is manifestly wrongvin prin-v rial.- Y v r The method of mixing as accomplished byy the apparatus herein disclosed, yisone calcu-*y ciple, since it tends to obstruct Vthe operation of those' naturallaws yWhichfgive the stucco its valuable propertiesas'a'building mate# lated to introduce what is believed to be the correct method of bringing` the; dry VVstucco `and the water into intimate contactwith the idea ofaordingmaximum water saturation. with Atherminimum *degreeV of me-g' chanicalagitatioii or mixing. .In a word, the j y processxinvolves the principle of interminmass collectedand li'ieaded lor rolled -into .a uniform texture bytreatment in the rotary( linorfstreamsiorls ra lets. of stucco .and t! Water into a semi-enclosed rotary chamber, whereby the mixing is primarily accoinpli'shed-in the air,v soto spealnvand the wet chamber ofsuch a natureas to preserve rather Y than.V break down Vthe crystalformations.

' A .preferred construction for an appara-V tus embodying the novel principlesofstucco mixing, is 4illustratedv in Athe accompanying drawings, lin which f Figure l is a general view in side elevation' of the mixing apparatus,

Figure2 Visa plan 'view of nfriixiiigA ap-.

' fparatus.y J l.

f VFigure-SLisa view inelevation of the mix- .ingcylinde'rr at the inlet end thereof. c

Figure .1g-is aview in end elevation'of'the rotative :cylinder mixer.

Figure 5 is a perspective view of a detailA i of the cylinder drive rollers; andv vvFigure is a viewV inhperspective of the inletend ofthe cylinder mixer Vshowing the I relative position of the stucco and Water de'-4 livery pipes.v

'.Referringtojthe general `arrangement of the mixing apparatus, the same comprises 'a feeding and`dischargingmechanism A for the dry stucco.v and the `rotary cylinder mixing `or kneading mechanism B. The function'of the stucco' feeding mechanism is'to discliarge'tlie stucco'in the form of a blastinto the mouth for inlet `end .of n the rotary cylin- Vder V1 of the mixing mechanismy B, the sameV being supported on trunnions with its axis inclined at a small angle of slope to'the hori-1 zontal to bring its'discharge end atV a' lower levelV thanits .inlet and'tliu's accelerate the V'down passage l at its discharge end leading Ytoa motor drivenfimpeller fan 5 which in `turn discharges through a horizontal pipe 6 ltoward the open inlet eiid of the rotarycy1inder l and yterminatinginfa downward bend`v (ia directed toward the bottom of the cylinder just inwardly from the mouth of the cylinder. The conveyor 2is preferablyv of thel screw type consisting of a horizontal Vduct 2L or closed troughin which; ascrew shaft vor propelling screw/7' ismounte'd, the same being, suitablyV journaled Vand belt-driven at `the required speed from a pulley 8Y mounted at .thel forward Yendef the shaft projecting beyond the end ofthe duet. The hopper isv positionedabovethe forward endof the duct and discharges at its lower 'end directly intoV Vthesame.y .The dry stuccois fedto the hopperY in any. suitable manner., .as for. instance, through a chute Yfrom aboveorkeptjiilled to feeding mechanism consists. 1.

a predetermined level` by a. conveyorI belt,V

leading from a suitable source of supply.

' The'impeller' fan 5 is mounted just below thev dischargeendv of the conveyor 2 vand may be' Yof any suitableor standardv design, al-

though one consistingof radial blades mount#r ed on `va'shaft enclosed'"withinV a' cylindric.

housing has been found satisfactory'7A` for the j A y i purpose. 'An electric. motorr'9lmounted Vadjacent-the fan f5 and directly connected to the shaft thereof-provides the'motivepower n for the fan.. As indicated in Figure 1, the' ico feeding apparatus as Well as the mixingy ap paratus is elevatedsomedistance above the fioorof the -plantinwhich'they are erected,-=

and hencer a" suitable!'supportingframe 10 is erected vto support them. .Thus ltheffeeding apparatus v:hassupporting frames at eachfend of the' conveyor 2 whieh'iieed not be described.

in detail,butV which, Vas lcan readily `observed, support the hopper andintake end of the conveyor'and the faii,fmotor and dis'-vv 'charge end ofthe conveyor, the `latrbeing supported through the pipe 4.V

f Themixing'apparatus B is mounted a iie iis i frame comprising four corner uprights 1l,V

crossmembers2 and diagonal braces 13, theV l vcylinderwithfits immediate supportingv and; driving members being carried by a separable i 120.:

movable frame or. cradle '14#l suspended-"or cradled Ybetween the pairs of upriglits 11,-11

of the stationary frame.

TheV cylinder lis j ournaledY in the mom ble' 7 frame ltt rotateV about its axis, .the framel in-.turn beingjournaled atitsliead end tothe stationary frame forilalimited vertical ad-r ljustment ofthe/.tail or discharge end-,ofthe cylinder rtovary tlietilt or inclination ,of its l ,axis to the horizontal.

`lReferring now V to thezconstructiong-of' the es lf cylinder' cradle, 14, the same preferably consists oftwo longitudinal side frame members 15 somewhat longer than the cylinder, these side frame members being shown as two angle irons bolted together, although they may be of vany convenient form. Extending above and between the side frame members and located atk each endand intermediate of said frame, is a bracket 16 made of strap iron bent in pyramid shape with a flat top portionto whichis bolted a journal bearing 17. Ex# tending llengthwise of the cradle and journaled in these aligned journal bearings 17 is a drive shaft 18. At some point on the shaft is a belt pulley 19 which drives the shaft from a suitable source of motive power. The head end of the cradle is pivotally'supported by pivot pins 2O passing through the upright supports 11 and near their upper ends and the longitudinal frame members. The tail or. lower end of the cradle is suspended by a bail 21 connected with the adjacent ends of the frame members 15 and having a central rod 21"L passing through an angle iron 22 extending crosswise between the upper ends of the uprights 11,y the rod being threaded and carrying a nut 21b which is turn-ed to elevate or lower the cradle tothe desired angle of inclination.

Referring now to the means for supporting the cylinder 1 in the tiltable frame or cradle, a cross-beam 23-23 extends between the longi'tudinal frame members 15-15 at each end of the cradle 14. Fixed to the underside of these crossbeams 28 of the cradle are sets of three journal bearings,l viz, a central bearing 24 and two outer bearings 25-25y on opposite sides of the central bearing, the latter being somewhat larger and extending a short distance below the side bearings. Extending lengthwise of the cradle and journal-ed at its ends in the center bearings 24--24 is a roller 26 from which the cylinder 1 is suspended for free rotation, said roller passing through the cylinder' and bearing against the upper surface thereof. Similarly there is ournaled in each of th-e side bearings a` shaft 27 extending exterior but'adj acent the cylinder, there being Y mounted on each shaft a pair of rolls or enlarged cylindric portions 28 located inwardly from the ends of thev cylinder and bearing against the exterior thereof at pointsremo'ved at angles of about 309 on opposite sides of the main or central supporting roller 26. Additional cross members 29-29 extending between the frame members 1515 and above the rolls 28 are preferably providedfor supporting pairs of shaft bearings 30-30 on either side of thev shafts 27-27 as shown in Figures 1 and 5. Still lanother cross 'beam 31 is supported between the, end portions of the central bearing supporting bracket which in turn-carries thrust roller 32 engaging in a ring 33 surroundingthe central portion of the cylinder and acts to hold the same against endwise movement toward its lowermostend (Figure 4). Y. "l, Mounted in the forward ends of each ,ofthe shafts 26, 27, 27 and the drive shaft 19, adjacent the forward or higher end of the cylinder, are sprocket ywheels 262272 272L and 19a respectively. Engaging these sprocket wheels isa drive chain 34 whereby the shafts 25, 26, 26 are driven from the main drive' shaft 19 in the same direction and at the same speed to drive the cylinderl 1 as shown by the arrows in Figure 3.

rIhe foregoing completes the construction of the mixing machine which consists, as already shown, of a fan ,or blower for introducing the stucco underair pressure through aV pipe opening into the inlet end of an openended cylinder or barrel mounted to turn about its axis which is tilted downwardly vto-` ward its discharge end.

The discharge end of the stucco delivery pipe 6 is shown as directed toward the bottom of the cylinder just inwardly fromits inlet end, although it may be directed upwardly or laterally at different angles if found to be more satisfactory, or spaced at a greater distance from the wall of the cylinder. Coacting with the discharge pipe for'the stucco is a water pipe 35 leading from a suitable source of water supply and terminating near the end of the stucco .pipe 6 in a nozzle`36 designed to discharge the desired Yvolume of water'in the form of a diverging stream into the path of y the stucco issuing from its pipe 6, thevolume of water dischargedbeing controlled by a valve 35a inthe pipe 35. Considerablelatii tude may be permittedin the exact arrange` ment. of the water and stucco discharge, the essential feature being the intermingling of the two iinely divided streams in such a manner that the stucco is subjected to a thorough and complete mixing with the water. In general, however, the two streams would 'con-` verge toward some point removed from :but in the direction of the inner surface of the cylinder, in some such manner as shown in Figure 6, so that the vtwo streams meet before the surface of the cylinder is reached. In this way, the stucco absorbs or takes up its required volume of water andthen is deli-vi ered against the revolvinginner surface ofy the cylinder in a completely' saturated and w'et state.v Thefcylinder Ais revolved7 at a moderate rate of speed,justsuiiicient tofke'ep' the wet mass progressing uniformly-:toward the discharge end, .ati the same time'fbeing rolled or kneaded into the properconsistency by the action of the cylinder and the'roller 26. `As the wet stucco adheres to the surface of the cylinder, it is carried upwardly until it encounters ther roller 26 which acts to scrape the stucco from the cylinder where upon it drops to the bottom and'again carried around and dropped until it works its way to the lower end of the cylinder andf'isrfinally discharged 'iito ai "conveyor belt! `or other' L receptacle.

" In the normal operation of the'v machine, the .rotationof the central supporting kroller yg-26'i'sjsufficient to revolve thecylinder With it atx@ uniform rspeed, With a possiblefslippage due to the stuccoffworking in between the lroller and the surfaceiof tliecylinder. This,

y however, is reducedV toda minimum by the rpairs of exterior drivefrolls`28-28 Which come. into playfwheneverV there is a .lifting of the cylinder from `the central roller, since obviously these rolls resist VanyiipWard movement'z'and immediately take the drivingV load.

At Votherftimes, they may: vonly idleragainst the'outer surface ofthe cylinder inrreadiness to drive When necessary, b ut at-all/ times serving to hold the cylinder in` vposition and against ylateral displacement. -lff desired, other materials may-be introduced into the stucco'at thefsameitime that its vmixture withv the Water takes place, orfat any time during thepassage of thewet stucco lthrough the cylinder. Thisis a matter ofproviding the `nece'ssaryfeeding and discharging pipesor ducts, and; positioning theml .to ldischarge at the'desired angle andL point inthe cylinder. ."By v'utilizing a vmachine such aslherein .de-v scribedglityis"possible to introduce the im` proved method of mixing referred -to at the 4 outset .1i-.of fthis.;l disclosure', namely, V`r`that ofV I bringing thestucco and WatertogetherA into intimatelfcontact, so -thatz eachY particle ,of

Y VVstucco?canabsorb its requisite .volume .of

W'ater,.iv'hich isibestbrought about by break- -ngilp bothy the stuccofand-Water. into spray-y like converging Ys'treams introduced under pressure intov a revolving cylinder,'the latter serving tofmiX thewvet. mass. suiciently to 14o give it a uniform""consistencyY butnot of a violent character sofas.V to retard the natural setting ofthe stucco. ';-Moreover,the mixing of, the 1 stuccovand'yvater being practically. .completed upon the meeting of the streams, the period requiredV for the mixing inthe cylinder is relatively short so that all agitation has been completed before the setting' process has scarcelyf commencedVV andy hence Vthe periodoftreatment is reduced to a minifmum. 1 I Y i '-.Mechanically-,g the .machine vhas itsadvan- Y "tagesbeingcomparatively simplein construction, operationjand maintenance. @lt occu-j i ciiicA disclosure herein rnadef.V

i pies 'butf-affractionof the space required for the common'for-m' ofisoakingfbeltgand m'e-frk j fchanical'imixers, and V'thereisl-no ibeltfto 're- I gplaceand adjustLg/i.

Obviously -V 1 numerous 'adaptations 1 of; the

fsame striictureymay bedesigiied to...a'cco1iiV plish the same purpose and therefore Ido notintend to limit myiinvention tovanyspe- Lclaim' asmyinvention: Y Y 11;;In a machine for the purposedescribed,

theicmbinationofa miXer, 'means for pneul Y said ,openingand1 s; .Thefmeihoa Qfffiiiiag a' plastic' mie can-.

Vmaticall'y impelling 1a v"dry material in lfinely divided form'intosaid mixer,'and a fluidV disA charge pipe directed toward said mixer `and arranged'to traverse the path of said' dry material as it enters said mixer. 7 Y fr 2. In a machine for thepurpose described,

opening, a liquidisupply'pipe havingfa discharge nozzle directedri'n-to saidv inletfopenl' `ing', `and means 'for pneumatically/-impelling a dry materia-l. in finely dividedform underY Y l pressure toward said. inlet -openingfand traversing the discharge from said liquid discharge pipe. Y y 5 8. :A mixingmachine comprising a-rotative Athe combination of a mixery having an inlet cylinder open-at'each end,l a pipe havingits dischargeend'. directed into oneendofsaid cylinder, rpneumatic means for` continuously feeding a drylmate'rialinfinely divided form and under pressure through said; pipe, and a liquid supply nozzlealsodirected into said sgr cylinder and' intersecting the pathy of the-" material and air delivered Vfrom'said pipe.

L A mixing apparatus comprising an aX- ially rotative open-ended cylinderr mountedV said cylinder, means for feeding adry material in 'finely divided form to saidrblower,

and means for supplying .Water under .pressure in the form of' a Aspray Jet intersecting.- the 90 Y. in substantially horizontal position, a blower lhaving its discharge directedinto oneend of path'fof the materialdischarged fromrsaid f' vblower adjacent said end of the cylinder.

t5; The method of Vmixing consisting of di-Y recting'a Ystream* of dry lmateiial infinely divided form by an airfblast into amixre` .ceiver, directing aspray. of liquid"toward said receiver aiidintersecting saidstream of dry material'andair before ,it enters'said `receiver, and thereafter knea'ding andtreating the Wet miX in the receiver.

6. In a machine forthe purposedescir'ibed,V j

the combination ofa mixer having an inlet f f opening, and means forpneumatically direct-1- ing ar stream Vof dry substances in finely di-` vided form and directingfluid substances in.'Y

finely'divided'forintowardthe inletopening i ofsaidy mixer under pressure, said-streams in'-l l teisectmgprior said mixer;

v7. In:` a machine forthe purpose- 'described,z.

the combination-'of arotativ'e ymixer havingV *y ari-inlet opening, pneumatic means for intro! dry. material.

Sisting` ofv impellijng a ldry pulverized matespray j et of .-waterinto said miXer:so'ashto'in-` to their fyint'roduction l* into rial lbyair. pressure, an air stream through an .orifice into gamechanicatmixer, directing a g vtersectfthe streamlofdry material andairv as Y of June, 1927.

SIDNEY C. CLARK. 

